Systems and methods for processing data entered using an eye-tracking system

ABSTRACT

A method for processing data entered using a keyboard and a keyboard capable of implementing the method is described. In one embodiment, the keyboard includes keys associated with at least one input data value and at least one multi-value key associated with at least two input data values. Each key includes a unit and each multi-value key includes a plurality of units and each input data value corresponds to at least one unit. The keyboard also includes an eye-tracking system that determines an area where a user is gazing by monitoring eye movements of the user, and an input value selection module coupled to units and to the eye-tracking system. The input value selection module determines probabilistically which input data value was entered based on a value received from at least one unit and on the area where the user is gazing.

This application is a continuation of U.S. patent application Ser. No. 12/748,642 titled, “Systems And Methods For Processing Data Entered Using An Eye-Tracking System,” filed Mar. 29, 2010, now issued as U.S. Pat. No. 8,576,175, which is a continuation of U.S. patent application Ser. No. 11/206,596 titled, “Systems And Methods For Processing Data Entered Using An Eye-Tracking System,” filed Aug. 18, 2005, now issued as U.S. Pat. No. 7,719,520 the entire disclosures of which are hereby incorporated by reference in their entireties.

BACKGROUND

The present invention relates to electronic devices, and more particularly to a system for processing data entered at an electronic device.

Handheld electronic devices, such as mobile phones, cameras and personal digital assistants (PDAs), offer a multitude of services and functions. For example, with the development of wireless technologies, many handheld devices are capable of connecting a user to a wireless network, such as the Internet, and allowing the user to send and receive information to and from other users via the wireless network. Moreover, many handheld devices can load and run software applications that allow the user to perform computing tasks.

While handheld devices can offer performance and versatility, the available services can sometimes be awkward to use because of device's size. Of particular concern is data entry, e.g., inputting text for an electronic message. Most handheld devices lack the space to provide a full keyboard for entering data and instead utilize several known techniques to allow the user to create words or number patterns. Nevertheless, each technique has its disadvantages.

For example, mobile phones typically provide a conventional number-key pad where each number key, i.e., key 2-9, is associated with three to four alphanumeric characters. By pressing specific keys, the user can form words. One method for creating words using the number-key pad uses a prediction algorithm that relies on an electronic dictionary of common words to predict a word based on the key(s) pressed. This technique, referred to as the T-9 technique, allows the user to tap a key, and a input value selection module in the device checks the dictionary to resolve ambiguities between the letters associated with the tapped key. Although the T-9 technique is a single-tap method that can allow fast data entry, it is not intuitive and can be deficient when two or more words are formed by the same sequence of tapped keys. In that instance, the T-9 technique cannot disambiguate between the words themselves and the user must resolve the ambiguity.

Another word forming technique using the number-key pad is referred to as multi-tapping. In multi-tapping, the user enters a particular letter by pressing the number key associated with the letter at least one time to scroll to the desired letter. Once the desired letter is found, e.g., displayed on the screen, the user must wait until the selection is committed and the letter is inputted before proceeding to the next letter. While multi-tapping allows the user to form words without ambiguity, it is time-consuming and awkward.

Other handheld devices, such as PDAs, can display a full keyboard on a touch screen, and the user selects letters by touching or tapping on the touch screen with a stylus. In other similar devices, a full miniature keyboard is provided in the device itself. In both instances, the size of the displayed and physical keyboard is reduced to accommodate the space limitations. Because the keys are small, they are difficult to see or press, making text entry awkward and slow as well as error prone.

Other text entry techniques exist but suffer from the same and other shortcomings described above. Most of these techniques, in addition to being awkward and slow, are not intuitive and/or require the user to spend much time practicing in order to become somewhat proficient.

SUMMARY

The present invention provides a method and system for entering data using an eye-tracking system in combination with a plurality of manually activated keys. In one embodiment, a keyboard includes keys each associated with at least one input data value and at least one multi-value key associated with at least two input data values. Each multi-value key includes a plurality of units. Each input data value corresponds to at least one unit. The keyboard also includes an eye-tracking system that determines an area where a user is gazing by monitoring eye movements of the user, and an input value selection module coupled to the units and to the eye-tracking system. The input value selection module determines probabilistically which input data value was entered based on a value received from at least one unit and on the area where the user is gazing.

In another embodiment, the keyboard includes a plurality of data input keys. Each input key is associated with at least one input data value and at least one data input key is a multi-value key associated with at least two input data values. The keyboard also includes an eye-tracking system that determines an area where a user is gazing by monitoring eye movements of the user and that determines an area covering portions of at least two data input keys. The keyboard also includes an input value selection module coupled to the plurality of data input keys and to the eye-tracking system that determines which input data value was entered based on a manually pressed data input key and on the area where the user is gazing.

In another embodiment, a method for processing data entered at a keyboard having a plurality of keys wherein each key is associated with an input data value and the input data value corresponds to the unit, the plurality of key including at least one multi-value key associated with at least two input data values includes assigning a plurality of units to each multi-value key, where each input data value corresponds to at least one unit, determining an area where a user is gazing by tracking the user's eye movement, detecting a manual selection of one of a key and a multi-value key, and determining probabilistically which input data value was entered based on a value received from at least one unit and on the area where the user is gazing.

In another embodiment, a method for processing data entered at an electronic device having a plurality of data input keys, where each data input key is associated with at least one input data value and at least one data input key is a multi-value key associated with at least two input data values, includes determining an area where a user is gazing by tracking the user's eye movement, where the area covers portions of at least two data input keys, detecting a manual selection of a data input key, and determining which input data value was entered based on the manually pressed data input key and on the area where the user is gazing.

DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The various features of the present invention and the manner of attaining them will be described in greater detail with reference to the following description, claims and drawings, wherein reference numerals are reused, where appropriate, to indicate a correspondence between the referenced items, and wherein:

FIG. 1A is a schematic diagram of an exemplary electronic device according to an embodiment;

FIG. 1B is a system block diagram of the electronic device according to an embodiment;

FIGS. 2A, 2B and 2C illustrate an exemplary multi-value key that is associated with four (4) input values according to an embodiment;

FIG. 3 is a flowchart illustrating a process for processing data entered at the electronic device according to an embodiment shown in FIGS. 1A, 1B, and 2A-2C;

FIG. 4 is a flowchart illustrating a process for calculating the probability factor for an input value according to one embodiment;

FIG. 5 is a schematic diagram of an exemplary electronic device according to another embodiment;

FIG. 6 is an illustration for a group of four (4) multi-value input keys according to an embodiment; and

FIG. 7 is a flowchart illustrating a process for processing data entered at the electronic device according to the embodiment shown in FIGS. 5 and 6.

DETAILED DESCRIPTION

The present invention relates to electronic devices, and more particularly to methods and systems for processing data entered at an electronic device. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.

According to one embodiment, an eye-gaze or eye-tracking system is incorporated into an electronic device that has data input keys that are associated with two or more input values. The electronic device uses the eye-tracking system to determine where a user is gazing while the user presses a data input key. Based on the eye-tracking and key press data, the electronic device is able to determine which of the two or more input values associated with the pressed key was entered.

FIG. 1A is a schematic diagram of an exemplary electronic device according to an embodiment and FIG. 1B is a system block diagram of the electronic device according to another embodiment. Referring to FIGS. 1A and 1B, the electronic device 10 includes a plurality of data input keys 20, an eye-tracking system 40, an input value selection module 30, and a display screen 50. The data input keys 20 can be arranged in rows and columns to form a keypad 25 on a face 12 of the electronic device 10. Each data input key 20 is associated with at least one input value 22, and at least one of the data input keys is a multi-value key 20 a that is associated with at least two data input values 22 a, 22 b, 22 c.

In a preferred embodiment, the eye-tracking system 40 is located on the same face 12 of the electronic device as the keypad 25. The eye-tracking system 40 tracks and records the movement of a user's eye(s) to determine an area where the user is gazing. The eye-tracking system 40 can use many different known techniques to monitor and track the user's eye movements. For example, the eye-tracking system 40 can utilize a technique known as corneal reflection, which directs an infrared light beam at the user's eye and measures the angular difference between the operator's mobile pupil and the stationary light beam reflection. Alternatively, the eye-tracking system 40 can scan the user's eye region with a scanning apparatus, e.g., television camera, and analyze the resulting image. Commercially available eye-tracking systems 40 that can be appropriate for the present invention include, for example, the QUICK GLANCE product developed by EyeTech Digital Systems of Mesa, Ariz.

In order to enter an input value, particularly one that is associated with a multi-value key 20 a, e.g., 22 a, the user locates the key 20 a with which the input value 22 a is associated and gazes at or near a corresponding representation of input value 22 a on the face of the key while pressing the key 20 a. The input value selection module 30 receives the eye-tracking data as well as the data related to the selected, e.g., manually pressed, key 20 a, and analyzes the received data to determine which input value 22 a was entered. The entered value 22 a is then preferably displayed on a screen 50.

In one embodiment, the accuracy with which the input value selection module 30 can determine the input value 22 a is improved by dividing each multi-value key 20 a into a plurality of units and associating each of the input values 22 a-22 c with at least one of the units. In a preferred embodiment, a representation of each input value is provided on a portion of the multi-value key that coincides with the associated unit(s). Each unit, in turn is associated with at least one pressure sensor that is capable of measuring a pressure asserted on the associated unit.

FIG. 2A is an illustration of an exemplary multi-value key 200 that is associated with four (4) input values 202 a-202 d. As is shown in FIG. 2B, the multi-value key 200 is divided into four (4) units 210 a-210 d and each of the input values 202 a-202 d is associated with one of the four units 210 a-210 d. In FIG. 2B, the multi-value key 200 is divided into four (4) substantially equal units 210 a-210 d merely for the sake of clarity. The number of units can be greater than four (4) and, in such circumstances, each input value, e.g., 202 a, can be associated with more than one unit 210 a. Similarly, the shape and size of each unit 210 can vary so long as each input value 202 a-202 d is associated with at least one unit 210.

As is shown in FIG. 2C, each unit 210 a-210 d may be associated with a pressure sensor 220 a-220 d that is capable of quantifying the amount of pressure asserted on the associated unit 210 a-210 d. Although not shown in FIG. 2C, each unit, e.g., 210 a, can be associated with more than one pressure sensor 220 a, and the shape and size of the pressure sensors 220 a-220 d can vary.

According to this embodiment, during data entry, the user can press the portion of the multi-value key on which the desired input value, e.g., 202 a, is provided, while gazing at the desired input value 202 a. Each pressure sensor 220 a-220 d measures the pressure asserted on its associated unit 210 a-210 d. The input value selection module 30 receives the pressure measurements from each of the pressure sensors 220 a-220 d along with the eye-tracking information and determines which of the associated input values 202 a-202 d was entered.

FIG. 3 is a flowchart illustrating a process for processing data entered at the electronic device 10 shown in FIGS. 1 and 2. The process begins by activating the keypad 25 (step 300), for example, by unlocking the input keys 20. The activation of the keypad 25 can also activate the eye-tracking system 40, which then monitors and records the user's eye movements (step 302). Activation of the keypad 25 and/or eye-tracking system 40 does not necessarily require an additional action or input, but can occur automatically when electronic device 10 is powered up. According to a preferred embodiment, the eye-tracking system 40 monitors and records, among other things, an area where the user is gazing, which input value(s) are in the area, and the amount of time the user's gaze rests on the input value(s).

When the user presses a multi-value key 200 (step 304) to enter a desired input value, e.g., 202 a, each pressure sensor 220 a-220 d measures the amount of pressure asserted on the associated unit 210 a-210 d. The pressure measurements associated with each unit 210 a-210 d are received by the input value selection module 30, which assigns to each input value 202 a-202 d a pressure weight, P, based on the corresponding pressure measurement(s) (step 306). In one embodiment, the pressure weight, P, can be a fraction ranging from zero (0), corresponding to the lowest pressure measurement, to one (1.0), corresponding to the highest pressure measurement.

Thus, in the example above where the user wants to enter input value “2” (202 a), the user preferably presses at or near the upper left hand corner of the input key 200, which is the portion of the key on which the “2” is provided and which substantially coincides with the unit 210 a associated with the input value 202 a. The pressure sensors 220 a-220 d measure the pressure asserted on each of the units 210 a-210 d. Because the user presses the portion of the key 200 substantially coinciding with the unit 210 a corresponding to the desired input value 202 a, the pressure weight, P, assigned to that input value 202 a will naturally be greater than the pressure weight assigned to an input value, e.g., 202 d, associated with a portion of the key 200 that was not pressed directly.

In addition to processing the pressure measurements, the input value selection module 30 also analyzes the eye-tracking data to determine how long the user was gazing at any of the input values 202 a-202 d prior to pressing the key 200 and assigns a gaze weight, G, to each input value 202 a-202 d based on the amount of time the user was gazing at the input value 202 a-202 d (step 308). Like the pressure weight, P, the gaze weight, G, can be a fraction ranging from zero (0), corresponding to the least amount of gaze time, to one (1.0), corresponding to the greatest amount of gaze time. Once the pressure weight, P, and gaze weight, G, for each input value 202 a-202 d are assigned, the input value selection module 30 calculates a probability factor, PF, for each input value (step 310).

FIG. 4 is a flowchart illustrating a process for calculating the probability factor for an input value, e.g., 202 a, according to one embodiment. For each input value 202 a-202 d, the assigned pressure weight, P, and gaze weight, G, are added to form a combined weight, C (step 400). The combined weight, C, for each input value 202 a-202 d is summed to form a total weight, T (step 402). The probability factor, PF, for each input value 202 a-202 d is calculated by dividing the combined weight, C, of the input value 202 a by the total weight, T (step 404). Thus, for an input value, i, the probability factor, PF(i) is determined by: PF(i)=C(i)/T

Referring again to FIG. 3, after the probability factor for each of the input values 202 a-202 d is calculated (step 310), the input value selection module 30 selects the input value having the greatest probability factor and displays that input value (step 312).

Based on the embodiment described above, the methods and systems disclosed take advantage of how the user intuitively enters data. That is, the user searches the keypad 25 for the key 20 that includes the input value 22 the user desires to enter. When the user's gaze falls upon the desired input value 22, the user instinctively focuses on the input value 22 and presses the portion of the key 20 displaying the input value 22. The various components of the electronic device 10 according to this embodiment monitor these actions to allow the user to enter the desired input value. The user can enter the desired input value with a single tap and need not wait a prescribed time before entering another input value. Accordingly, this embodiment is easy to use and provides fast data entry.

In another embodiment, illustrated in FIG. 5, the accuracy with which the input value selection module 30 can determine the input value 22 a is improved by defining a plurality of gaze areas 14 on the face 12 of the electronic device 10 a. According to this embodiment, each defined gaze area 14 covers a portion of at least two data input keys 20, and preferably is associated with one input value in each of the at least two data input keys 20. Moreover, in this embodiment, input value selection module 30 can determine the input value 22 a even when each input key 20 includes only one input sensor that is associated with multiple input values 202 a assigned to the input key 20. The input sensor is activated when the associated input key 20 is pressed. The input sensor may be a simple momentary switch providing two binary values (0 or 1) or may be a pressure sensor as described above.

For example, FIG. 6 is an illustration for a group of four (4) multi-value input keys 200 a-200 d according to this embodiment of the present invention. As is shown, one gaze area 14 a includes an area corresponding to one input value of each of the four (4) keys 200 a-200 d. Another gaze area 14 b includes a different area corresponding to a different set of input values in each of two (2) keys 200 c, 200 d. The gaze areas 14 a, 14 b do not overlap, and therefore, any particular input value, e.g., 202 d, is associated with only one gaze area 14 a.

Referring again to FIG. 5, each gaze area 14 can also include a focal point 16, which is preferably near the center of the gaze area 14. The focal point 16 can be a feature, such as a dot, so that the user can focus on the point 16. Alternatively, the focal point 16 can be unmarked and merely defined as near or around the center of the gaze area 14. Other ways of designating a gaze area 14 and its focal point 16 are available as those skilled in the art would readily appreciate.

Referring again to FIG. 6, during data entry, the user can press the multi-value key, e.g., 200 a, associated with the desired input value, e.g., 202 d, while gazing at or near the focal point 16 a associated with the gaze area 14 a. The input value selection module 30 receives the key press data along with the eye-tracking information and determines which of the input values 202 a-202 d associated with the pressed key 200 a was entered by selecting the input value 202 d associated with the gaze area 14 a.

FIG. 7 is a flowchart illustrating a process for processing entered data using the electronic device 10 according to the embodiment shown in FIGS. 5 and 6. The process begins by activating the keypad 25 (step 700), for example, by unlocking the input keys 20 or by powering up the electronic device 10. The activation of the keypad 25 can also activate the eye-tracking system 40, which then monitors and records the user's eye movements (step 702). According to a preferred embodiment, the eye-tracking system 40 monitors and records, among other things, at which gaze area 14 the user is gazing and, optionally, an amount of time the user is gazing at a particular gaze area 14. Preferably, the user focuses on the focal point 16 of the gaze area 14 so that the eye-tracking system 40 can determine the gaze area 14 more accurately by increasing the margin for error.

When the user presses a multi-value key 200 a (step 704) to enter a desired input value, e.g., 202 d, the input value selection module 30 determines which input key 200 a was pressed (step 706) and determines at which gaze area 14 a the user is gazing (step 708) during a time period either immediately before and/or after the key 200 a was pressed. The time period can be short such that the gazing action is substantially simultaneous with the key pressing event. On the other hand, the time period can be longer to ensure that the input value selection module 30 detects the correct gaze area 14 a. Once the gaze area 14 a and the pressed key 200 a are determined, the input value selection module 30 displays the entered input value 202 d associated with both the pressed key 200 a and the gaze area 14 a (step 710).

This embodiment also takes advantage of how the user intuitively enters data. That is, the user searches for the key 200 a that is associated with the desired input value 202 d and presses the key 200 a while gazing at a designated focal point 16 a near the desired input value 202 d. The user can enter the desired input value 202 d with a single tap and need not wait a prescribed time before entering another input value. Accordingly, this embodiment is also easy to use and provides fast data entry.

Although the embodiments described above each utilize a keypad 25, the principles described herein can also be used with a standard sized keyboard that includes multi-value keys. For example, in a typical QWERTY keyboard, the key associated with the input value “2” is also associated with the character “@.” Utilizing the systems described herein, the user can enter the character “@” by gazing at the “@” and typing the key. In another example, foreign language keyboards often require the user to press a sequence of keys to enter a symbol. With the system of the present invention, the symbol can be associated with a key and can be entered with a single tap.

Moreover, the aspects described herein can also be combined with other letter prediction techniques, such as a word-based letter prediction technique that is based on a dictionary or an application-specific set of words. In this aspect, a word-based technique yields a probability W for a given letter, where the larger W is the more probable the given letter. The probability factor PF calculated by the input value selection module 30 can be combined with W to produce a combined probability weight CW. Depending on how PF and W are combined, either technique can be given priority. For example, let CW=PF×W. Here, both techniques are given equal priority. Alternatively, let CW=(PF)^(1/n)×W. Here, the key-press-gaze technique is given higher priority than the word-based technique.

According to aspects described herein, single tap data entry is enabled by incorporating an eye-tracking system into an electronic device that has data input keys that are associated with two or more input values. The electronic device uses the eye-tracking system to determine where a user is gazing while the user presses a data input key. Based on the eye-tracking and key press data, the electronic device is able to determine which of the two or more input values associated with the pressed key was entered.

The present invention has been described in accordance with the embodiments shown, and one of ordinary skill in the art will readily recognize that there could be variations to the embodiments, and any variations would be within the spirit and scope of the present invention. Software written according to the present invention is to be stored in some form of computer-readable medium, such as memory, CD-ROM or transmitted over a network, and executed by a input value selection module. Consequently, a computer-readable medium is intended to include a computer readable signal which, for example, may be transmitted over a network. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims. 

We claim:
 1. A keyboard comprising: a plurality of keys, each associated with an input data value wherein each key includes a unit and the input data value corresponds to the unit, the plurality of keys including at least one multi-value key associated with at least two input data values, wherein each multi-value key includes a plurality of units and each input data value corresponds to at least one of the plurality of units; an eye-tracking system for determining an area where a user of the keyboard is gazing by monitoring an eye movement of the user; and an input value selection module coupled to the units of the plurality of keys and to the eye-tracking system; wherein the input value selection module determines probabilistically which input data value was entered based on a value received from at least one unit of the units and on the area where the user is gazing.
 2. The keyboard of claim 1 further comprising: a plurality of pressure sensors coupled to the input value selection module, wherein each unit of the plurality of units of the at least one multi-value key is associated with at least one of the plurality of pressure sensors and each unit of the plurality of keys is associated with at least one of the plurality of pressure sensors and wherein each of the pressure sensors is configured to measure a pressure asserted on the associated unit of the plurality of keys including the at least one multi-value key; wherein the input value selection module concurrently analyzes the pressure measurements and the area at which the user is gazing to determine which input data value was entered.
 3. The keyboard of claim 2 wherein the input value selection module is configured for: assigning a pressure weight to each of the input data values associated with the plurality of keys including the at least one multi-value key, the pressure weight corresponding to measured pressured asserted on the unit corresponding to the input data value; assigning a gaze weight to each of the input data values based on an amount of time that the area at which the user is gazing coincides with the unit corresponding to the input data value; combining the pressure weight and the gaze weight of each input data value; and entering the input data value based on the combined pressure and gaze weights.
 4. The keyboard of claim 2 wherein the area at which the user is gazing substantially coincides with a unit associated with an input data value.
 5. The keyboard of claim 1 wherein the keyboard is associated with a handheld device.
 6. The keyboard of claim 5 wherein the handheld device is either a camera, a telephone, or a personal digital assistant.
 7. A keyboard comprising: a plurality of data input keys, wherein each input key is associated with at least one input data value and at least one data input key is a multi-value key associated with at least two input data values; an eye-tracking system for determining an area where a user is gazing by monitoring an eye movement of the user, wherein the eye-tracking system determines an area covering portions of at least two of the plurality of data input keys; and an input value selection module coupled to the plurality of data input keys and to the eye-tracking system; wherein the input value selection module determines which input data value was entered based on a manually pressed data input key and on the area where the user is gazing.
 8. The keyboard of claim 7 comprising a plurality of defined gaze areas, at least one gaze area overlapping at least two multi-value keys.
 9. The keyboard of claim 8 wherein each defined gaze area is associated with one input data value in each of a first and a second multi-value key.
 10. The keyboard of claim 8 wherein each defined gaze area is associated with one input data value in each of a first, a second, a third and a fourth multi-value key.
 11. The keyboard of claim 9 wherein the input value selection module enters the input data value that is associated with the gaze area and that is associated with the manually pressed multi-value key.
 12. The keyboard of claim 7 wherein the keyboard is associated with a handheld device.
 13. The keyboard of claim 12 wherein the handheld device is either a camera, a telephone, or a personal digital assistant.
 14. A method for processing data entered at a keyboard having a plurality of keys associated with an input data value, the plural of keys including at least one multi-value key associated with at least two input data values, the method comprising: assigning a unit to each key; assigning a plurality of units to each multi-value key, wherein each input data value corresponds to at least one unit; determining an area where a user is gazing by tracking the user's eye movement; detecting a manual selection of one of a key and a multi-value key; and determining probabilistically an input data value entered based on a value received from at least one unit and on the area where the user is gazing.
 15. The method of claim 14 further comprising: assigning each unit of the plurality of keys including the at least one multi-value key to at least one pressure sensor, wherein each of the pressure sensors is configured to measure and quantify a pressure asserted on the associated unit of the plurality of keys including the at least one multi-value key; and concurrently analyzing the pressure measurements and the area at which the user is gazing to determine which input data value was entered.
 16. The method of claim 15 further comprising defining the area at which the user is gazing as substantially coinciding with a unit associated with an input data value.
 17. The method of claim 15 further comprising: assigning a pressure weight to each of the input data values associated with plurality of keys including the at least one multi-value key, the pressure weight corresponding to measured pressured asserted on the unit corresponding to the input data value; assigning a gaze weight to each of the input data values based on an amount of time that the area at which the user is gazing coincides with the unit corresponding to the input data value; combining the pressure weight and the gaze weight of each input data value; and entering the input data value based on the combined pressure and gaze weights.
 18. A method for processing data entered at a keyboard having a plurality of data input keys, each data input key being associated with at least one input data value and at least one data input key being a multi-value key associated with at least two input data values, the method comprising: determining an area where a user is gazing by tracking the user's eye movement, wherein the area covers portions of at least two data input keys; detecting a manual selection of a data input key; and determining which input data value was entered based on the manually pressed data input key and on the area where the user is gazing.
 19. The method of claim 18 further comprising defining a plurality of gaze areas, at least one gaze area overlapping at least two multi-value keys.
 20. The method of claim 19 wherein each defined gaze area is associated with one input data value in each of a first and a second multi-value key.
 21. The method of claim 20 wherein determining which input data value was entered includes identifying the input data value that is associated with the gaze area and that is associated with the manually pressed multi-value key.
 22. A non-transitory computer readable medium containing program instructions for entering data using a keyboard having a plurality of data input keys, wherein each data input key is associated with at least one input data value and at least one data input key is a multi-value key associated with at least two input data values, the computer readable medium comprising program instructions for: determining an area where a user is gazing by tracking the user's eye movement, wherein the area covers portions of at least two data input keys; detecting a manual selection of a data input key; and determining which input data value was entered based on the manually pressed data input key and on the area where the user is gazing.
 23. A non-transitory computer readable medium containing program instructions for entering data using a keyboard having at least one multi-value key associated with at least two input data values; the computer readable medium comprising program instructions for: assigning a unit to each key; assigning a plurality of units to each multi-value key, wherein each input data value corresponds to at least one unit; determining an area where a user is gazing by tracking the user's eye movement; detecting a manual selection of one of a key and a multi-value key; and determining probabilistically which input data value was entered based on a value received from at least one unit and on the area where the user is gazing. 